In splicing electrical cables, such as high voltage insulated cables, both the central conductors and the surrounding cylindrical layers of insulation must be joined. The central metallic conductors can be connected in any suitable manner such as by using crimp connectors and butt welding.
A continuous insulation layer is provided over the joined connectors by removing insulation from the ends of the conductors before joining, and then placing a layer of uncured insulation material over the joined connectors. The uncured insulation is subsequently cured under heat and pressure allowing the uncured insulation material to cure and fuse with the adjacent insulation remaining on the cables.
The curing operation is critical since improper curing will result in a defective splice. Defective splices will not have a uniform layer of cured insulation surrounding the joined conductors and will include air voids or pores.
Electrical cables used in oil wells to power pumps located many feet below the surface must be capable of performing satisfactorily under extreme adverse conditions of heat, mechanical stress and pressure. Such cables experience down-hole pressures which can be in the hundreds of thousands of pounds per square inch. Any voids or air pockets existing in the insulation receive gas forced into them at high pressures over a period of time. When the head of well fluid is pumped down rapidly or when the cable is relatively quickly extracted from the well, insufficient time is provided for the gas trapped in the voids to bleed off. As a result, the insulation on the cable tends to expand like balloons and can rupture, rendering the cable useless.
Conventional systems for producing an insulated splice between two cables suffer from numerous disadvantages. The apparatus are complex and expensive, and are difficult to use, particularly in the field. Additionally, the conventional apparatus often do not maintain an adequately constant pressure during the curing operation to avoid the formation of air voids in the splice insulation.
Examples of such conventional devices are disclosed in U.S. Pat. No. 4,084,307 to Schultz et al and U.S. Pat. No. 4,236,949 to Horsma et al.
Another mold device for forming a splice between electrical cables by applying heat and pressure is disclosed in U.S. patent application Ser. No. 404,152, entitled "Apparatus and Method for Producing an Insulated Connection Between Electrical Cables", of Neuroth et al, the subject matter of which is hereby incorporated by reference.